August 15, 1901] 



NA TURE 



379 



athlete at any instant may be found. M. Marey's ex- 

 cellent work in chronophotography is again illustrated by 

 the analysis of the long jump (Fig. 4). The columns 

 are to be read from right 

 to left and from top to 

 bottom. .\s in the former 

 diagram, a composite pic- 

 ture has been made from 

 several consecutive images. 

 In this instance, owing to 

 the rapid movements of 

 the jumper, the figures 

 have less tendency to be 

 confused by superimposi- 

 tion. By eliminating e\ery 

 other image, a clear and 

 comprehensive representa- 

 tion of all the actions has 

 been obtained — actions 

 which no language could 

 describe with sufficient 

 accuracy. The means of 

 determining the e.xtent and 

 the duration of these move- 

 ments is as perfect as 

 possible. The chronograph 

 sliows that the interval 

 between the images is 

 I 14th second, whilst the 

 metric scale gives the 

 length of the jump as 

 4'69m. The same method 

 of measurement shows that 

 the space traversed by the 

 jumper in i 14th second 

 was 52 cm., giving him a 

 velocity of 728 m. per 

 second. If the detail of 

 Fig. 2 is closely studied, 

 it will be seen that different 

 points of the jumper's body 

 do not cover the same 

 space in the same time. 

 For example, the head is 

 displaced with unequal 

 velocities, because the arms 

 and legs are at each suc- 

 cessive moment in different 

 positions. Several other 

 analyses of the movements 

 of celebrated athletes, 

 French and American, were 

 obtained, and in all cases 

 much light has been thrown 

 on the rapid movements 

 of the limbs in the case 

 of clearing hurdles in a 

 race. 



The evidence collected 

 in each section of the in- 

 quiry instituted by the 

 commission of physiology 

 and hygiene should prove 

 itself to be most interesting 

 and valuable matter, since 

 it should lead to a complete 

 modification of the system 

 of athletic training and 

 establish it on the study 

 01 nature itself, instead of 

 on theories devoid of ex- 

 perimental foundation and 



often contradictory. M. Marey's methods of time measure- 

 ment are very excellent, simple and effective, and a study 



.NO. 1659, VOL. 64] 



of his work, " Le Mouvement," ought to stimulate English 

 experimentalists to work in the same direction, which 

 should prove itself to be a fruitful field (or research in 



Fig. 4. — Long jump by Sweeney. 



a country in which athletic exercises of every kind are so 

 vigorously practised by all classes. 



